1. Field of the Invention
This invention relates to hose couplers, and more particularly it relates to an improved vacuum hose coupling device and method of connecting hoses useful to carpet cleaners.
2. Description of Prior Art
Various coupling devices are known in the art.
U.S. Pat. No. 4,625,998 to Donald A. Draudt (1986) discloses a swivel hose ‘end piece connector’ but there is no locking, sealing, or release mechanism provided in association with the connection of two hoses. U.S. Pat. No. 5,257,836 to Peter J. Smith (1993) provides a quick and easy pipe coupling for field workers but it uses an ‘elastomeric’ sealing means of which are known in the art to degrade and leak over time, especially in the presence of water based chemicals commonly used in carpet cleaning. U.S. Pat. No. 5,407,236 to Ernst Schwartz, et al. (1995) discloses an innovative hose coupling which could be modified for use by carpet cleaners but the coupling can only be disengaged with the aid of an auxiliary tool.
For carpet cleaners, coupling devices for releasably connecting sections of vacuum hose have evolved from single insert to multi-component types. The three most common coupling devices in use by carpet cleaners are:                (1) Single insert coupler: comprising a symmetric tube body of about twice the length of the diameter of the hose being coupled is typically made of hardened plastic or metal with circumferential notches or barbs. The insert is ‘wedged’ into each hose end and the notches or barbs are meant to lock the coupler in place and thus hold the hoses together.        (2) Three-part coupler: two end piece connectors are each fixedly threaded onto each hose end, then an insert as described above is wedged into the free end of each end piece connector thus coupling the hoses.        (3) Four part coupler: the same two end piece connectors and insert are connected as described above, then a pair of straps straddle the coupling device and prevent it from being pulled apart.        
There are numerous problems with these prior art couplings:
Single insert coupler: Vacuum hoses are typically made of hardened plastic with little elasticity and the insert is typically made of an even more rigid material; this makes for a physically trying experience wedging the insert into each hose end. During use, hot fluids and air passing thru the sections of hose cause differential swelling between the hose and insert and this swelling can result in leakage of air and fluid around the hose end and insert. Eventually, this coupling device fails as the swelling becomes so extreme that the insert slips out of the hose end and may even never to seal properly again. Another problem with ‘insert’ couplings is that since the insert is of smaller inner diameter (“ID”) than that of the hose itself, flow is restricted. Strands of hair and other debris accumulate at these restrictions over time and create a physical blockage in the hose. The jagged hose ends being fully exposed, detract from the appearance of this coupling device.
Three part coupler: The two end piece connectors hide the jagged hose ends and thus improve the appearance of the coupler plus the two end pieces connectors provide a more secure attachment to the hose ends by means of threads along their interior surface whereby each end piece connector engages circumferential grooves along the perimeter surface of its respective hose end. Unfortunately, the same insert as described above is typically used to couple the two end pieces connectors and this weak connection allows this coupling device to pull apart under tension just like the single insert coupling device. Plus, the insert restricts flow, and accumulates debris. Manufacturers seem to have added parts, expense, and complexity yet still have not solved the problems—flow restriction, leakage, and hose separation.
Four part coupler: This style of coupling device solves the ‘separation’ problem by using two straps that are secured to vacuum hose beyond the coupler itself then buckled together. However, these straps add girth to the hose causing it to ‘hang-up’ on obstacles along its path. The straps also add complexity, labor, parts, and expense. And the insert is still required, so leakage still occurs; especially as the hoses heat and swell with age. Even with the straps, the insert still restricts flow and collects debris.
With the advancements in the art, it seems that coupling devices have become:                (i) more complex in design,        (ii) more difficult to use,        (iii) more expensive, and        (iv) less streamlined.        
And they still haven't solved the two main functional problems of:                (v) leakage, and        (vi) flow restriction.        